Here is a somewhat old thread that helps a little to answer the question. Link here.
In short, usually it will try to rebel back to the country it was from originally. In the off chance that, it has been completely conquered and wiped off the map before day change or the sometimes odd chance that it decides to rebel to somewhere else, it will try to look for a "close" neighbor that has high morale. This closeness seems arbitrary at times. It may share a land or sea border with such a nation and rebel to them. So in general, would say you probably can't pull a province away from someone else on purpose.

I don't know the exact criteria that CoW uses for a rebelling country to choose who they are going to join. But I suspect the following 4 factors: 1) Original country; 2) Close neighbor with high morale; 3) Close neighbor with good economy; and 4) Close neighbor with high VP count.

Look at it this way: A province from west Xinjiang that rebels will probably join Texas because when you go to the left from the province (if we say the map is a sphere) then the closest high morale country is Texas. Hope i helped.

Average moral with strong military and high good will wordwide.
All three components are important for dicision od revolts.

It goes for North and South too. A procince from South Africa can end up in Norway.

I think its average morale

I also think it is average morale. Which practically means that, if the "original" country is extinct and there is an AI neighbor (i.e. a country that only has the original cores) it will most probably rebel to that country (tough to beat an average morale of over 90%).

In addition to morale, there is a "reputation" that your country has, for starting wars and things like that. In elite AI games it is used for a "most dreaded" list, and being neighbors with a highly dreaded country will cause the Elite AI to declare war.


Now reputation is not displayed in games without the elite AI, but of course it is still calculated, as you get the pop up messages about declaring war affecting your reputation.

I have no evidence that reputation plays a factor in choosing who to join after a rebellion, but I expect it is also a factor. It is clearly not a simple decision so it is likely based on a formula that factors in the suggested items above, and a few more:

Average morale
distance to capital
distance to nearest province
Reputation
army strength
And perhaps more.

Each of these has a "weight" in the calculation, and someone comes out on top, even if it is improbable.



I should cross reference this thread with my guide to morale and rebellions.

forum.callofwar.com/index.php?…ions-and-province-morale/

In case someone starts here in the future trying to understand why rebellions happen.